Related papers: Maser emission during post-AGB evolution

We present asymptotic giant branch (AGB) models of solar metallicity, to allow the interpretation of observations of Galactic AGB stars, whose distances should be soon available after the first release of the Gaia catalogue. We find an…

CONTEXT: Asymptotic giant branch (AGB) stars are in one of the latest evolutionary stages of low to intermediate-mass stars. Their vigorous mass loss has a significant effect on the stellar evolution, and is a significant source of heavy…

The physical mechanism(s) responsible for transitioning from a spherical Asymptotic Giant Branch (AGB) star to an asymmetric post-AGB (pAGB) object is poorly understood. In particular, excess momenta in the outflows of pAGB objects suggest…

H2O (22 GHz) and SiO masers (43, 86, 129 GHz) in the bipolar proto-planetary nebula OH231.8+4.2 were simultaneously monitored using the 21-m antennas of the Korean VLBI Network in 2009-2015. Both species exhibit periodic flux variations…

Low- and intermediate-mass stars evolve through the asymptotic giant branch (AGB), when an efficient mass-loss process removes a significant fraction of their initial mass. A substantial increase in the mass-loss rate at the end of the AGB…

We examine the envelope properties of asymptotic giant branch (AGB) stars as they evolve on the upper AGB and during the early post-AGB phase. Due to the high mass loss rate, the envelope mass decreases by more than an order of magnitude.…

Mass loss on the Asymptotic Giant Branch provides the origin of planetary nebulae. This paper reviews several relevant aspects of AGB evolution: pulsation properties, mass loss formalisms and time variable mass loss, evidence for…

The IRAS source, 19312+1950, exhibits SiO maser emission, which is predominantly detected in evolved stars enshrouded by a cold molecular envelope. In fact, the mojority of the observational properties of IRAS 19312+1950 is consistent with…

With the aim of investigating whether stellar sources can account for the >10^8 Msun dust masses inferred from mm/sub-mm observations of samples of 5<z<6.4 quasars,we develop a chemical evolution model which follows the evolution of metals…

We present the results of SiO maser observations at 43GHz toward two AGB stars using the VLBA. Our preliminary results on the relative positions of the different J=1-0 SiO masers (v=1,2 and 3) indicate that the current ideas on SiO maser…

The post-main sequence evolution of stars of intermediate or large masses is notoriously complex. In the recent past, a number of workshops and meetings have focused on either the Asymptotic Giant Branch of intermediate mass stars, or the…

We use a gaseous model and a semi-analytical approach to study the evolution of a super-massive central gaseous object (a super-massive star, (SMS from now on) in an AGN and its evolution by interactions with the surrounding stellar system.…

We performed a millimetric survey of a sample of 24 post-AGB stars aimed to search for emission from circumstellar matter, in order to investigate the physical properties of the outer parts of the envelopes. The observations were conducted…

The formation of silicates in circumstellar envelopes of stars evolving through the AGB is still debated given the uncertainties affecting stellar evolution modelling, the description of the dust formation process, and the capability of…

We summarise the evolution and nucleosynthesis in AGB and Super-AGB stars. We then examine the major sources of uncertainty, especially mass-loss.

The mass loss properties of carbon AGB stars are not very well constrained at present. A variety of empirical or theoretical formulae with different parameterisations are available in the literature and the agreement between them is…

Dynamical stellar-evolution modeling through the AGB phase reveals that radial pulsations with very fast-growing amplitudes develop if the luminosity to mass ratio of stars with tenuous envelopes exceeds a critical limit. An instability…

The detected variety in chemistry and circumstellar shell morphology of the limited sample of Galactic post-AGB stars is so large that there is no consensus yet on how the different objects are linked by evolutionary channels. The…

Abundance anomalies observed in globular cluster stars indicate pollution with material processed by hydrogen burning. Two main sources have been suggested: asymptotic giant branch (AGB) stars and massive stars rotating near the break-up…

Context. The transition from the spherically symmetric envelopes around asymptotic giant branch (AGB) stars to the asymmetric morphologies observed in planetary nebulae is still not well understood, and the shaping mechanisms are a subject…